# Copyright (c) 2012 OpenStack Foundation.
# All Rights Reserved.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.

from neutron_lib.api.definitions import network as net_def
from neutron_lib.api.definitions import port as port_def
from neutron_lib.api.definitions import subnet as subnet_def
from neutron_lib.api.definitions import subnetpool as subnetpool_def
from neutron_lib import constants
from neutron_lib.db import constants as db_const
from neutron_lib.db import model_base
from neutron_lib.db import standard_attr
import sqlalchemy as sa
from sqlalchemy import orm
from sqlalchemy import sql

from neutron.db.network_dhcp_agent_binding import models as ndab_model
from neutron.db import rbac_db_models


# NOTE(ralonsoh): move to neutron_lib.db.model_base
class HasInUse:
    """NeutronBaseV2 mixin, to add the flag "in_use" to a DB model.

    The goal of this class is to allow users lock specific database rows with
    a shared or exclusive lock (without necessarily introducing a change in
    the table itself). Having these locks allows the DB engine to prevent
    concurrent modifications (e.g. the deletion of a resource while we are
    currently adding a new dependency on the resource).

    "read_lock_register" takes a shared DB lock on the row specified by the
    filters. The lock is automatically released once the transaction ends.
    You can have any number of parallel read locks on the same DB row. But
    you can not have any write lock in parallel.

    "write_lock_register" takes an exclusive DB lock on the row specified by
    the filters. The lock is automatically released on transaction commit.
    You may only have one write lock on each row at a time. It therefor
    blocks all other read and write locks to this row.
    """

    @classmethod
    def write_lock_register(cls, context, exception, **filters):
        # we use `with_for_update()` to include `FOR UPDATE` in the sql
        # statement.
        # we need to set `enable_eagerloads(False)` so that we do not try to
        # load attached resources (e.g. standardattributes) as this breaks the
        # `FOR UPDATE` statement.
        num_reg = context.session.query(
            cls).filter_by(**filters).enable_eagerloads(
                False).with_for_update().first()
        if num_reg is None:
            raise exception

    @classmethod
    def read_lock_register(cls, context, exception, **filters):
        # we use `with_for_update(read=True)` to include `LOCK IN SHARE MODE`
        # in the sql statement.
        # we need to set `enable_eagerloads(False)` so that we do not try to
        # load attached resources (e.g. standardattributes) as this breaks the
        # `LOCK IN SHARE MODE` statement.
        num_reg = context.session.query(
            cls).filter_by(**filters).enable_eagerloads(
                False).with_for_update(read=True).first()
        if num_reg is None:
            raise exception


class IPAllocationPool(model_base.BASEV2, model_base.HasId):
    """Representation of an allocation pool in a Neutron subnet."""

    subnet_id = sa.Column(sa.String(36), sa.ForeignKey('subnets.id',
                                                       ondelete="CASCADE"),
                          nullable=True)
    first_ip = sa.Column(sa.String(64), nullable=False)
    last_ip = sa.Column(sa.String(64), nullable=False)

    def __repr__(self):
        return f"{self.first_ip} - {self.last_ip}"


class IPAllocation(model_base.BASEV2):
    """Internal representation of allocated IP addresses in a Neutron subnet.
    """

    port_id = sa.Column(sa.String(36), sa.ForeignKey('ports.id',
                                                     ondelete="CASCADE"),
                        nullable=True)
    ip_address = sa.Column(sa.String(64), nullable=False, primary_key=True)
    subnet_id = sa.Column(sa.String(36), sa.ForeignKey('subnets.id',
                                                       ondelete="CASCADE"),
                          nullable=False, primary_key=True)
    network_id = sa.Column(sa.String(36), sa.ForeignKey("networks.id",
                                                        ondelete="CASCADE"),
                           nullable=False, primary_key=True)
    revises_on_change = ('port', )


class Route:
    """mixin of a route."""

    destination = sa.Column(sa.String(64), nullable=False, primary_key=True)
    nexthop = sa.Column(sa.String(64), nullable=False, primary_key=True)


class SubnetRoute(model_base.BASEV2, Route):

    subnet_id = sa.Column(sa.String(36),
                          sa.ForeignKey('subnets.id',
                                        ondelete="CASCADE"),
                          primary_key=True)


class Port(standard_attr.HasStandardAttributes, model_base.BASEV2,
           model_base.HasId, model_base.HasProject):
    """Represents a port on a Neutron v2 network."""

    name = sa.Column(sa.String(db_const.NAME_FIELD_SIZE))
    network_id = sa.Column(sa.String(36), sa.ForeignKey("networks.id"),
                           nullable=False, index=True)
    fixed_ips = orm.relationship(IPAllocation,
                                 backref=orm.backref('port',
                                                     load_on_pending=True),
                                 lazy='selectin',
                                 cascade='all, delete-orphan',
                                 order_by=(IPAllocation.ip_address,
                                           IPAllocation.subnet_id))

    mac_address = sa.Column(sa.String(32), nullable=False)
    admin_state_up = sa.Column(sa.Boolean(), nullable=False)
    status = sa.Column(sa.String(16), nullable=False)
    device_id = sa.Column(sa.String(db_const.DEVICE_ID_FIELD_SIZE),
                          nullable=False)
    device_owner = sa.Column(sa.String(db_const.DEVICE_OWNER_FIELD_SIZE),
                             nullable=False)
    ip_allocation = sa.Column(sa.String(16))

    __table_args__ = (
        sa.Index(
            'ix_ports_network_id_device_owner', 'network_id', 'device_owner'),
        sa.Index('ix_ports_device_id', 'device_id'),
        sa.UniqueConstraint(
            network_id, mac_address,
            name='uniq_ports0network_id0mac_address'),
        model_base.BASEV2.__table_args__
    )
    api_collections = [port_def.COLLECTION_NAME]
    collection_resource_map = {port_def.COLLECTION_NAME:
                               port_def.RESOURCE_NAME}
    tag_support = True

    def __init__(self, id=None, tenant_id=None, project_id=None, name=None,
                 network_id=None, mac_address=None, admin_state_up=None,
                 status=None, device_id=None, device_owner=None,
                 fixed_ips=None, **kwargs):
        super().__init__(**kwargs)
        self.id = id
        self.project_id = project_id or tenant_id
        self.name = name
        self.network_id = network_id
        self.mac_address = mac_address
        self.admin_state_up = admin_state_up
        self.device_owner = device_owner
        self.device_id = device_id
        # Since this is a relationship only set it if one is passed in.
        if fixed_ips:
            self.fixed_ips = fixed_ips

        # NOTE(arosen): status must be set last as an event is triggered on!
        self.status = status


class DNSNameServer(model_base.BASEV2):
    """Internal representation of a DNS nameserver."""

    address = sa.Column(sa.String(128), nullable=False, primary_key=True)
    subnet_id = sa.Column(sa.String(36),
                          sa.ForeignKey('subnets.id',
                                        ondelete="CASCADE"),
                          primary_key=True)
    order = sa.Column(sa.Integer, nullable=False, server_default='0')


class Subnet(standard_attr.HasStandardAttributes, model_base.BASEV2,
             model_base.HasId, model_base.HasProject, HasInUse):
    """Represents a neutron subnet.

    When a subnet is created the first and last entries will be created. These
    are used for the IP allocation.
    """

    name = sa.Column(sa.String(db_const.NAME_FIELD_SIZE))
    network_id = sa.Column(sa.String(36), sa.ForeignKey('networks.id'),
                           nullable=False)
    # Added by the segments service plugin
    segment_id = sa.Column(sa.String(36), sa.ForeignKey('networksegments.id'))
    subnetpool_id = sa.Column(sa.String(36), index=True)
    # NOTE: Explicitly specify join conditions for the relationship because
    # subnetpool_id in subnet might be 'prefix_delegation' when the IPv6 Prefix
    # Delegation is enabled
    subnetpool = orm.relationship(
        'SubnetPool', lazy='joined',
        foreign_keys='Subnet.subnetpool_id',
        primaryjoin='Subnet.subnetpool_id==SubnetPool.id')
    ip_version = sa.Column(sa.Integer, nullable=False)
    cidr = sa.Column(sa.String(64), nullable=False)
    gateway_ip = sa.Column(sa.String(64))
    network_standard_attr = orm.relationship(
        'StandardAttribute', lazy='selectin', viewonly=True,
        secondary='networks', uselist=False,
        load_on_pending=True)
    revises_on_change = ('network_standard_attr', )
    allocation_pools = orm.relationship(IPAllocationPool,
                                        backref='subnet',
                                        lazy="selectin",
                                        cascade='delete')
    enable_dhcp = sa.Column(sa.Boolean())
    dns_nameservers = orm.relationship(DNSNameServer,
                                       backref='subnet',
                                       cascade='all, delete, delete-orphan',
                                       order_by=DNSNameServer.order,
                                       lazy='selectin')
    routes = orm.relationship(SubnetRoute,
                              backref='subnet',
                              cascade='all, delete, delete-orphan',
                              lazy='selectin')
    ipv6_ra_mode = sa.Column(sa.Enum(constants.IPV6_SLAAC,
                                     constants.DHCPV6_STATEFUL,
                                     constants.DHCPV6_STATELESS,
                                     name='ipv6_ra_modes'),
                             nullable=True)
    ipv6_address_mode = sa.Column(sa.Enum(constants.IPV6_SLAAC,
                                          constants.DHCPV6_STATEFUL,
                                          constants.DHCPV6_STATELESS,
                                          name='ipv6_address_modes'),
                                  nullable=True)
    # subnets don't have their own rbac_entries, they just inherit from
    # the network rbac entries
    rbac_entries = orm.relationship(
        rbac_db_models.NetworkRBAC, lazy='joined', uselist=True,
        foreign_keys='Subnet.network_id',
        primaryjoin='Subnet.network_id==NetworkRBAC.object_id',
        viewonly=True)
    api_collections = [subnet_def.COLLECTION_NAME]
    collection_resource_map = {subnet_def.COLLECTION_NAME:
                               subnet_def.RESOURCE_NAME}
    tag_support = True


class SubnetPoolPrefix(model_base.BASEV2):
    """Represents a neutron subnet pool prefix
    """

    __tablename__ = 'subnetpoolprefixes'

    cidr = sa.Column(sa.String(64), nullable=False, primary_key=True)
    subnetpool_id = sa.Column(sa.String(36),
                              sa.ForeignKey('subnetpools.id',
                                            ondelete='CASCADE'),
                              nullable=False,
                              primary_key=True)


class SubnetPool(standard_attr.HasStandardAttributes, model_base.BASEV2,
                 model_base.HasId, model_base.HasProject):
    """Represents a neutron subnet pool.
    """

    name = sa.Column(sa.String(db_const.NAME_FIELD_SIZE))
    ip_version = sa.Column(sa.Integer, nullable=False)
    default_prefixlen = sa.Column(sa.Integer, nullable=False)
    min_prefixlen = sa.Column(sa.Integer, nullable=False)
    max_prefixlen = sa.Column(sa.Integer, nullable=False)

    # TODO(imalinovskiy): drop this field when contract migrations will be
    #  allowed again
    # NOTE(imalinovskiy): this field cannot be removed from model due to
    # functional test test_models_sync, trailing underscore is required to
    # prevent conflicts with RBAC code
    shared_ = sa.Column("shared", sa.Boolean, nullable=False,
                        server_default=sql.false())

    is_default = sa.Column(sa.Boolean, nullable=False,
                           server_default=sql.false())
    default_quota = sa.Column(sa.Integer, nullable=True)
    hash = sa.Column(sa.String(36), nullable=False, server_default='')
    address_scope_id = sa.Column(sa.String(36), nullable=True, index=True)
    prefixes = orm.relationship(SubnetPoolPrefix,
                                backref='subnetpools',
                                cascade='all, delete, delete-orphan',
                                lazy='selectin')
    rbac_entries = sa.orm.relationship(rbac_db_models.SubnetPoolRBAC,
                                       backref='subnetpools',
                                       lazy='selectin',
                                       cascade='all, delete, delete-orphan')
    api_collections = [subnetpool_def.COLLECTION_NAME]
    collection_resource_map = {subnetpool_def.COLLECTION_NAME:
                               subnetpool_def.RESOURCE_NAME}
    tag_support = True


class Network(standard_attr.HasStandardAttributes, model_base.BASEV2,
              model_base.HasId, model_base.HasProject):
    """Represents a v2 neutron network."""

    name = sa.Column(sa.String(db_const.NAME_FIELD_SIZE))
    subnets = orm.relationship(
        Subnet,
        lazy="selectin")
    status = sa.Column(sa.String(16))
    admin_state_up = sa.Column(sa.Boolean)
    vlan_transparent = sa.Column(sa.Boolean, nullable=True)
    qinq = sa.Column(sa.Boolean, nullable=True)
    rbac_entries = orm.relationship(rbac_db_models.NetworkRBAC,
                                    backref=orm.backref('network',
                                                        load_on_pending=True),
                                    lazy='joined',
                                    cascade='all, delete, delete-orphan')
    availability_zone_hints = sa.Column(sa.String(255))
    mtu = sa.Column(sa.Integer, nullable=False,
                    default=constants.DEFAULT_NETWORK_MTU,
                    server_default=str(constants.DEFAULT_NETWORK_MTU))
    dhcp_agents = orm.relationship(
        'Agent', lazy='selectin', viewonly=True,
        secondary=ndab_model.NetworkDhcpAgentBinding.__table__)
    api_collections = [net_def.COLLECTION_NAME]
    collection_resource_map = {net_def.COLLECTION_NAME: net_def.RESOURCE_NAME}
    tag_support = True


class NetworkSubnetLock(model_base.BASEV2):
    """Auxiliary table to lock each network subnet updates.

    This table is used to synchronize the subnet creation per network. If
    several requests to create subnets on a network are processed at the same
    time (even in different servers), this database lock will prevent the
    creation of several subnets with overlapping CIDRs by updating the network
    register in the table each time a subnet is created.
    """
    __tablename__ = 'network_subnet_lock'

    network_id = sa.Column(sa.String(36),
                           sa.ForeignKey('networks.id', ondelete='CASCADE'),
                           primary_key=True)
    subnet_id = sa.Column(sa.String(36))
